The Music Player Daemon - Developer's ManualIntroduction
This is a guide for those who wish to hack on the MPD source
code. MPD is an open project, and we are always happy about
contributions. So far, more than 150 people have contributed
patches.
This document is work in progress. Most of it may be incomplete
yet. Please help!
Code Style
indent with tabs (width 8)
don't write CPP when you can write C++: use inline
functions and constexpr instead of macros
the code should be C++11 compliant, and must compile with
GCC 4.9 and
clang 3.4
Some example code:
static inline int
foo(const char *abc, int xyz)
{
if (abc == NULL) {
LogWarning("Foo happened!");
return -1;
}
return xyz;
}
Hacking The Source
MPD sources are managed in a git repository on git.musicpd.org.
Always write your code against the latest git:
git clone git://git.musicpd.org/master/mpd.git
If you already have a clone, update it:
git pull --rebase git://git.musicpd.org/master/mpd.git master
You can do without "--rebase", but we recommend that you rebase
your repository on the "master" repository all the time.
Configure with the options . Enable as many plugins as possible,
to be sure that you don't break any disabled code.
Don't mix several changes in one single patch. Create a
separate patch for every change. Tools like
stgit help you with that. This way,
we can review your patches more easily, and we can pick the
patches we like most first.
Basic stgit usage
stgit allows you to create a set of patches and refine all of
them: you can go back to any patch at any time, and re-edit it
(both the code and the commit message). You can reorder
patches and insert new patches at any position. It encourages
creating separate patches for tiny changes.
stgit needs to be initialized on a git repository: stg init
Before you edit the code, create a patch: stg new
my-patch-name (stgit now asks you for the commit message).
Now edit the code. Once you're finished, you have to "refresh"
the patch, i.e. your edits are incorporated into the patch you
have created: stg refresh
You may now continue editing the same patch, and refresh it as
often as you like. Create more patches, edit and refresh them.
To view the list of patches, type stg series. To go back to a
specific patch, type stg goto my-patch-name; now you can
re-edit it (don't forget stg refresh when you're finished with
that patch).
When the whole patch series is finished, convert stgit patches
to git commits: stg commit
Submitting Patches
Send your patches to the mailing list:
mpd-devel@musicpd.org (subscribe
here)
git pull requests are preferred. Regular
contributors can get an account on
git.musicpd.org, but any public git repository will do.
Development ToolsClang Static Analyzer
The clang static
analyzer is a tool that helps find bugs. To run it on
the MPD code base, install LLVM and clang. Configure MPD to
use clang:
./configure --enable-debug CXX=clang++ CC=clang ...
It is recommended to use ,
because the analyzer takes advantage of
assert() calls, which are only enabled in
the debug build.
Now run the analyzer:
scan-build --use-c++=clang++ --use-cc=clang make
The options and
are necessary because it invokes
cc for actually compiling the sources by
default. That breaks, because MPD requires a C99 compiler.